Spark timer for hammers



June 20, 1939. c, CHARLES 2,163,336

SPARK TIMER FOR HAMMERS Filed April 5, 1937 2 Sheets-Sheet 1 June 20,1939- c. L. CHARLES SPARK TIMER FOR HAMMERS Filed April 5, 1937 2Sheets-Sheet 2 m 0 I 0 w f v z 67? I I CarZj U/mrZea; @W%

m g l. L

Patented June 20, 1939 SPARK TIMER FOR HAMMEBS 'Carl L. Charles,Winnetka, 11]., assigncr to Gas Tool Patents Corporation, a corporationof Delaware Application April 5, 1987, Serial No. 135,185 14 Claims.(Cl. 123-1465) This invention relates to internal combustion percussivehammers, and more particularly to spark timers therefor.

One feature of this invention is that it provides means for varying thetime of commencement of ignition; another feature is that it providesmeans for varying the duration of flow of ignition current; anotherfeature of this invention is that it provides improved mounting meansfor the ignition points; yet another feature. of this invention is thata mounting is provided sealing the points from a contact withinflammable vapors; still another feature of this invention is thatmeans is provided for varying the durationof flow of ignition current inaccordance with the temperature of the hammer, which means may be eithermanual or automatic; other features and advantages of this inventionwill be apparent from the following specification and the drawings, inwhich:

Figure 1 isa vertical elevation, partly in sec tion, of an internalcombustion percussive tool embodying this invention; Fig. 2 is afragmentary sectional view of the hammer shown in Fig. 1; Fig. 3 is anelevation of the timer housing and mounting; Fig. 4 is a view, partly insection, along the line 44 of Fig. 3; Fig. 5 is a detailed sectionalview of a modified form of timer; Fig. 6 is a detailed sectional view ofa timer particularly designed for varying the duration of flow ofignition current; and Fig. 7 is a sectional view of a timer having meansfor automatically varying' the timing.

The internal combustion hammer or percussive tool illustrated herewithhas a cylinder ill having a piston hammer ll freely reciprocal thereinand adapted to impart blows to a tool at the bottom of the hammerthrough the anvil II. A piston return spring assembly l3 urges thepiston upwardly. The hammer is provided with a charge forming device Iprovided with a tank adapted to contain a liquid fuel, a carburetor, andthe necessary manifold passages to enable a combustible charge to bedrawn into the chamber l5 beneath the piston and thereafter transferredto the combustion chamber l6 above the piston through the passage II, inaccordance with known two-cycle engine practice.

The hammer is provided with an ignition system including a spark plug l8and a timer l9. An ignition unit including a battery or other source ofcurrent and a buzzer operated spark coil is connected, in accordancewith known practice, to the hammer through a cable having a high tensionand a low tension circuit therein. The

high tension circuit is connected to the spark plug by the wire 20,while the low tension circuit is connected to the timer by the wire 2|,thus enabling the timer to control ignition by control of the currentflow therein. It will be noted that the piston II is provided with a camsurface 22 adapted to actuate, upon reciprocation of the piston, a camfollower or plunger in the timer I9.

The hammer shown herein as one embodiment of this invention is of thesame fundamental type as that shown in Mould Patents Nos. 1,868,754 and1,997,072, for example, and the general mode of operation of the hammeris fully described therein.

In order to secure efilcient operation of an ll internal combustionengine it is, of course, necessary to have the high tension spark orignition means initiated at a particular time with respect to thereciprocation of the piston in the cylinder. Too early ignition resultsin knocking, over heating, and other troubles; and too late ignitionre-. sults in poor combustion efliciency, loss of power, slower actionof the hammer, and the like. The point at which the spark should beinitiated also varies somewhat in accordance with the temperature of thehammer, and it is preferable to provide means for adjusting the actionof the timer in this respect to vary the timing of the ignition.

Where ignition of the make" type is used, as disclosed on thisparticular embodiment of the invention, high tension sparks continue toflow across the spark plug electrodes as long as the points in the timerare closed. This is, of course, a drain on the battery and therefore itis preferable not to have ignition current flow any longer thannecessary. In order to start a hammer of this type, however, it isnecessary to have a much'longer time of ignition current flow thanthatwhich will effectively operate the hammer after it is warmed up. Itis thus also desirable to provide means, as here disclosed, forshortening the duration of flow of ignition current as the hammer warmsup. It will be seen that proper control of the timing of the hammer thusincludes one or both of the two elements discussed above: the first, thepoint or time of initiation of ignition; and second, the duration ofignition current flow.

In the particular timer illustrated in Figs. 2 to 4, the cylinder III isprovided with an opening 23 therethrough transverse to the axis of thecylinder. A sleeve member 24 is held therein by studs 25 tapped into thecylinder wall or a boss provided therefor. Within the sleeve 24 is alonthe cam surface 22 on the piston. A coil spring gitudinally movableplunger 28 having a roller 21 on the inner end thereof adapted tocontact 28, axially disposed with relation to the plunger,

' biases 0r urges it against the piston, sothat reciprocation ormovement of the piston in the cylinder effects longitudinal movement ofthe plunger 28.

The plunger 28 has movably mounted therein and coaxial therewith asecond longitudinally movable plunger 28. The inner end of the plunger29 is provided with a stop Ill adapted to contact a shoulder on theplunger 28 to prevent outward movement of the second plunger withrespectto the first. A coil spring ll surrounds the second plunger andlies between a shoulder there-- on and a shoulder on the plunger 26,yieldingly urging the second plunger outwardly with respect to the firstplunger. It will be thus seen that the two plungers may telescope withineach other to the extent of the space provided between the stop 30 andthe roller 21, so that the plunger 26 may continue to moveoutwardly as aresult of movement of the piston even though the second plunger 29 hasceased outward movement.

A pair of cooperating ignition points 32 and 23 are provided. The point33 is adiustably mounted on the end of the plunger 29 and adapted to bemoved toward and into contact with the point 32 upon movement of thefirst plunger 26. This point 22 is mounted on a member 24 passingthrough insulated washers l5 and 36 on each side of an opening 31 in thehousing 38. The outer end of the member 34 is threaded, and a nut 39 isprovided for locking the member in place. x

The points 32 and 23 are operatlvely connected in the low tensionignition circuit to control ignition as a result of a change ofrelationship, that is, from open to closed relationship, or vice versa.The point 32 is insulated from the hammer body and connected to the wire2| through the connecting lug 4l. The point 28 is grounded to the hammerthrough the plungers in contact with the cylinder wall. It will be notedthat the timing of the hammer may be varied by moving the point 33toward or away from its cooperating point to vary the instant ofinitiation of ignition with respect to movement of the piston. The lug40 engages a flattened portion of the member 34 and acts as a wrench forholding the member while the nut 39 is drawn up tight. It is preventedfromfalling out of place when the nut is slightly loosened by theshoulder portions engaging the washer.

The springs providing the necessary bias on the two plungers are hereshown as nested coil springs in substantially coaxial relationship. The

spring II is of lighter construction than 2|, so

that during the latter part of the movement, when the plunger 26 ispushing against both springs, there will not be undue wear on the camsin-face. The particular arrangement shown has been found to be veryrugged as well as efilcient. The plungers and springs are so arrangedthat the terrlfic vibration of the hammer when in operation causeslittle or no wear and difiilculty with the parts. The springsparticularly have been found to stand up much better than fiat springsof various types originally used in the hammers. 4

Shims may be inserted between the outer or plate portion of the member24 and the wall of the cylinder, so that when the studs 26 drawn up thefinal position of the cam follower with respect to the piston and camsurface thereon will be affected thereby. The presence of theseshimsserves two purposes. They might be inserted or removed to change theinitiation point, to compensate for wear of the cam surface or camfollower, or both. Adjustment here also assures the minimum over travelof the point it necessary to avoid intermittent separation of thepointfrom vibration and spring surge during the period it is desired tohave them stay 7 closed. That is, if the points Just barely touch andthen stay in that position for an appreciable time interval, surges inthe springs 20 and SI, vibrations in the body of the hammer, or both,may cause the points; to separate momentarily and thus interruptignition. Where there is considerable over travel of the first plunger 2the spring'll is put under suillcient tension to insure that the points22 and. 32 remain in contact during the interval that contact isdesired. In the particular embodiment of this invention illustrated inFig. 2, for example, there is about forty-seven thousandths of an inchdiiference between the low point and the high. point on the cam surfaceof the piston, so that the plunger 26 moves about this distance duringreciprocation of the piston. The points are preferably set with aninitial gap of only about five thousandths of an inch, so that there isthus about forty-two thousandths of an inch over travel to insuremaintenance of the points closed.

In order to facilitate original adjustment of the shims in the shop orin the field, the outer face ll of the plunger 2 is arranged to be aboutforty-five thousandths of an inch from the outer face 82 of the fiatportion of the member 24 when the member 26 abuts the shoulder 28. Inorder to insure proper initial position of the plunger and points withrespect :to the piston it is then only necessary to bring the highpointof the cam surface on the piston adjacent the roller 21, so that theplunger 26 is moved as far to the left as it would be in operation, andthen to insert or move shims beneath the flat portion of the member 24until the outer surface ll of the plunger 26 is flush with the surface82. Thismakes a very convenient assembly or field adjustment, and onewhich is independent of wear on the cam surface or roller.

The housing it is so constructed and arranged as to seal the points fromatmosphere. This is a desirable feature, since it prevents-any chance ofa sparking at the points igniting combustible vapors which may bepresent in the air about the hammer. The tank in the charge formingdevice l4 contains a supply of relatively volatile inflammable fiuid,usually gasoline, which fluid is open to atmosphere through the tankfiller cap, the air intake to the carburetor, and the like. Portions ofunburned charge are frequently exhausted from the cylinder, moreover,through the exhaust port 4|. Priming of the hammer when it is cold inorder to facilitate starting also increases the gasoline vapors presentin the atmosphere immediately about the hammer. when these hammers areused near gas mains, in mines, or the like, combustible vapors, or gasesmay be present which are of an even more .explosive nature. Enclosingthe points in a housing which seals them from atmosphere, therefore, isa safety feature tending to prevent undesired ignition of these .vapors.a

In the modification of this invention illustrated are inFig. 5. thelongitudinally movable plunger 42 1g has mounted in the end thereof apoint adapted to cooperate with a point 44 mounted in a secondlongitudinally movable plunger 45 slidably iournalled in the housing46.. Coil springs 41 and 48, which may be duplicates, are providedurging both plungers in the direction toward the cylinder. A reinforcingbeam 46 extends across between studs. similar to 2.5.

In the particular modification being described the entire housing 46 isinsulated from the cylinder of the hammer by the appropriate insulatingwashers 50 and 5!, so that the connecting lug 52 is not insulatedfromthe housing. When reciprocation of the piston moves the plunger 42to the left, the point 43 makes contact with the point 44 and continuedoutward motion of the plunger 42 is absorbed by movement of the secondplunger 45. I

In this particular modification a sleeve 53\is shown as threaded intothe opening in the wall of the cylinder Iii. The base plate or sleevemem-. ber 54 is bolted to the cylinder in the same manner as waspreviously described in connection with Fig. 3. The outer end of thethreaded sleeve 53 provides a stop or shoulder against which the plate54 is bolted. Rotation of the threaded sleeve 53 prior to drawing downthe studs holding plate .54 on the cylinder thus adjusts the point ofinitiation of ignition with respect to reciprocation of the piston.- Itis to be understood that the spacing between the points may be adjusted,if desired, by insertion or removal of shims between the housing 46 andthe base plate 54.

Another modification is illustrated in Fig. 6. wherein the timer isparticularly designed to enable variation of the duration of ignitioncurrent in accordance with temperature changes in the hammer. Alongitudinally movable plunger 55 is adapted to be moved through contactwith the cam surface on the piston, as previously described. and hasmounted on the outer end thereof the point 56 adapted to cooperate withthe second point 51 of the pair of points. This latter point is mountedon a movable member 58 slidablymounted in a bearing 59. A coil spring 60biases the movable member and point 51 toward the cylinder, but anadjustable stop 6| prevents movement beyond a certain desired pos tion.so that the points 56 and 51 are separated during the major portion ofthe movement of the piston. The movable member 58 also has mountedthereon a point 62 adapted to cooperate with a point 63 mounted on amovable means here shown it to remain in contact therewith duringinitial movement to the left of the member 56. A stop against which thespring 64 abuts is here shown I as a stud 65 threaded into an insulatingbushing in the housing 66 and manually adjustable through rotation ofthe outer knob or head.

In this particular embodiment, as the piston rises in the cylinder andcompresses the charge above it, the plunger 55 moves outwardly as aresult of its contact with the gently sloping cam. surface on the pistonuntil, at the desired instant, the point 56 contacts the point 51 andcompletes the low tension circuit to energize the spark coil and ignitethe charge. As the piston continues to rise the plunger 55 carries themember 58 outwardly with it, the points 62 and 63 still maintaining aclose relationship. After a predetermined amount of movement of themember 58, however, the spring 64 contacts the end of the stop screws 66and further outward movement of the plunger and member causes the points62 and 63 to change their relationship .and separate. This breaks theignition circuit, even though points 56 and 51 are still closed.

The modification shown and described in the preceding paragraphs givesfull control of the timing, and is economic of battery power. Ad-Justment of the stop screw 6i varies the point at which ignition isinitiated with respect to the stroke or reciprocation of the piston; androtatiorr'of the stop screw 65 varies the length of time during whichignition current fiows. This latter adjustment is so .arranged as to beeasily operable at any time. in order that the length of current flowmay be reduced as the temperature of the hammer rises. When the hammeris being started cold the screw 66 is backed oil so that there isarelatively long sparking period to take advantage of delayed ignition.As the hammer warms up the stop screw may be turned further inward tovary the period during which the circuit is closed so that the ignitioncurrent, generally supplied by a light dry battery, shall not be.

any greater drain on the battery than necessary.

A modification designed to provide automatic control of the periodduring which ignition current fio'ws is illustrated in-Fig. 7. Asdescribed in connection with Fig; 6, a longitudinally movable plunger 61and a movable member 68 carry points 69 and 16, respectively, whichpoints are adapted to be closed at a desired instant to complete-theignition circuit and initiate sparking across the electrodes of theplug. The outer end of the member 66 alsocarries a point ll adapted tocooperate with a point I! normally in contact therewith.

The point 12, however, is here shown as mounted on a movable support 13which comprises a pair of metals having different coeflicients ofexpansion. The member 13 thus assumes different free positions inaccordance with the temperature of the hammer. The bimetallic movableelement is so arranged that when the hammer is cold the point I2 followsthe point ll outwardly and remains in contact therewith throughout arelatively long interval. As the hammer warms up the free or unbiasedposition of the movable mounting means 13 moves further towards thecylinder, so that the points 'II and 12 remain in contact for a shorterinterval of piston movement. The period of ignition current flow is thusautomatically regulated to effect easy starting and battery economy whenthe hammer is warmed up and working.

While I have shown and described certain embodiments of my invention, itis to be understood that it is capable of many modifications. Changes,therefore, in the construction and arrangement may be made withoutdeparting from the spirit and scope of the invention as disclosed in theapigniting said charge, said system including a pair of cooperatingignition points for controlling said ignition; a longitudinally movableplunger actuated by reciprocation of said piston through con- 4 creases"tact with a cam suriace thereon and elective to move one of said pointstoward the other; a coil spring opposing said movement; a second longi--tudinally movable plunger so constructed and arranged asto permitiurthermovement of said first plunger after said points have come intocontact; and s.- secondcoil spring opposing the movepiston for breakingsaid circuit; and means for adjusting the period during which saidcircuit is closed to vary the timing 01' said ignition.

4. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder, a piston reciprocable therein, said piston beingadapted to impart impacts to a tool, and means for supplying saidcylinder with a combustible charge, including: an ignition circuit forigniting said charge; a longitudinally movable plunger actuated bymovement of said piston through contact with a cam suriace thereon; apair of cooperating points in said circuit adapted to contact each otherupon movement of said plunger to close said circuit; a second pair ofcooperating points in said circuit, normally biased together, adapted toseparate upon further movement or said plunger to break said circuit;and means for adjustingthe period during which said circuit is closed tovary the timing of said ignition.

5. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder, a piston freely reciprocable therein, said pistonbeing adapted to impart impacts to a tool, and means for supplying saidcylinder with a combustible charge, including: an ignition circuit forigniting said charge; a longitudinally movable plunger -actuated bymovement oi said piston through contact with a cam surface thereon; 'apair oi'cooperatingvpoints in said circuit adapted to contact each otherupon movement of said plunger to close said circuit; a second pair ofcooperating.

points in said circuit; a movable member having mounted thereon one oreach of said pairs oi points; movable means on which the other of saidsecond pair of points is mounted, said means being so constructed as tomaintain said second pair oi points in contact upon initial movement oisaid member eii'ected by closing oi said first pair of points by saidplunger, but to'cause said points to separate upon further movement ofsaid member.

6. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder, a piston freely reciprocable therein, said pistonbeing adapted to impart impacts to a'tool, and means for supplying saidcylinder with a combustible charge, including an ignition circuit forigniting said charge; means actuated by move ment of said piston forclosing said circuit, said 7 means including a pair of cooperatingpoints;

meansactuated upon further movement-of said piston for breaking saidcircuit, said means including a second pair of points; mounting meansfor one of said second pointstending to maintainsaidpointsin closerelationship; andvariable stop means for varying the instant ofseparation oi'saidsecondpairoipointa- '1. Ignition apparatus ioraninternal combused to impart impacts in a tool, and means for upplying:said cylinder with a combustible charge, including an ignition circuitfor igniting said charge: a longitudinally movable plunger actuated bymovement oi said piston through contactwithacamsuriacethereon;apairoicooperating points in said circuit adapted to contact each otherupon'movement of said plunger to close said circuit; a second pair oicooperating points in said circuit; a movable member having mountedthereon one oi each of said pairs of points; spring mounting means forthe other 01' said-second pair of points, said spring means tending tomaintain said second pair of points in contact during movement of saidmember eifected vby closing of said first pair oi points by saidplunger; and manually adjustable stop means to vary the instant at whichmovement of saidspring means is arrested to separate said second p'airotpoints.

8. Ignition apparatus for an internal combustion percussive hammerhaving a; piston therein, including: a pair of cooperating ignitionpoints having operative connections for initiating flow of ignitioncurrent upon contact thereof, at least one 01 said points being movable;actuating means for moving said movable point into and out oi contactwith; the other in accordance with the reciprocation of said piston inthe hammer; and means for-automatically adjusting the duration orflow-oi said igniti a current in accordance with the temperature I thehammer.

9. Ignition apparatus for an internal combustion percussive hammeradapted to impart impacts to a tool, and means for supplying saidcylinder with a combustible charge, including: an ignition circuit forigniting said charge, said circuit including a pair ofcooperatingvignition points for initiating current flow upon contactthereof; actuating means for moving one of said points into and out ofcontact with the other in accordance withthe reciprocation oi saidpiston, said actuating means being operable by'contact with said piston;and means for breaking saidcircuit after it has been closed i'or'adesired'period, said means automatically varying thelength of saidperiod in accordance with the temperature of the hammer.

10. Apparatus oi the character claimed in claim 9, including a secondpair oi points in said circuit.

11. Apparatus oi the character claimed in claim cuit and a thermallyresponsive .element upon which one oi said second pair of points ismounted. I

12. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder. a piston reciprocable therein, said piston beingadaptedtoimpartimpactstoatoohandmeansior ving a cylindena piston freelyreciprocable therein, said piston being to close said circuit; a secondpair of cooperating points in said circuit; a movable member havingmounted thereon one 01 each of said pairs of points; a thermallyresponsive movable means on which the other of said second pair ofpoints is mounted, said means being so constructed as to maintain saidsecond pair of points in contact for a desired period dlu'ing movementof said member eflected by closing of said first pair of points by saidplunger, whereby said period is automatically varied in accordance withthe temperature of the hammer.

13. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder. a piston freely reciprocal therein, said piston beingadapted to impart impacts to a tool, and'means for supplying saidcylinder with a combustible charge, including: an ignition system forigniting said charge, said system including a pair of cooperatingignition points for controlling said ignition upon a change ofrelationship thereof, at least one 01' said points being movable; alongitudinally movable plunger actuated by reciprocation of said piston,said plunger having one of said points mounted thereon; means wherebysaid plunger may continue further movement after said points have comeinto contact; and means for mounting said plunger in said hammer, saidmeans being adjustable to move said plunger toward or away from saidpiston.

14. Apparatus of the character claimed in claim 13, wherein saidmounting means for the plunger has a point thereon adapted to registerwith a cooperating point on said plunger when said plunger is moved toits farthest outer position by said piston.

CARL CHARLES.

